The present invention relates to the field of distributed constant type electromagnetic delay lines and more specifically relates to a super high speed such distributed constant type electromagnetic delay line which is suitable for handling a super high speed signal having a rise time of 1 ns or less, and which is of a super compact type construction which is suitable to be formed as a chip.
Conventionally, there is a known sort of distributed constant type electromagnetic delay line, in which a zigzag strip, in the form of a bent over microstrip line, is formed over a major surface of a dielectric plate, whose other surface is provided with a ground electrode. However, such a conventional type of distributed constant electromagnetic delay line suffers from the disadvantage that there is an excessive negative coupling between the bent line intervals, and this sets a limit to the compactness of the design and impairs the characteristics of the distributed constant electromagnetic delay line as far as handling super high speed signals is concerned.
Therefore, the present inventor previously proposed a novel type of distributed constant electromagnetic delay line in U.S. patent application Ser. No. 686,399 which has now issued as U.S. Pat. No. 4,570,136; it is not intended hereby to admit this prior proposal as prior art to the present application except to the extent otherwise prescribed by law. In this prior proposal, in a distributed constant electromagnetic delay line in which a zigzag strip and a ground electrode oppose one another with a dielectric body interposed therebetween, the zigzag strip was bent over first and second imaginary planes which opposed one another with a spacing of T therebetween, in an alternating manner at a pitch of P, with the spacing T and the pitch P being selected so that the ratio T/P was between zero and unity, so that as a consequence the negative coupling arising from the zigzag strip line is appropriately reduced or canceled, and so that super compact design and improvement in electronic properties are obtained.
However, the distributed constant electromagnetic delay line of this above identified proposal was not yet perfect from the point of view of compactness and manufacturing convenience, and its electronic properties were not yet ideal.